In rotary grinding wheel art, it is necessary to support and carry a rotatable grinding wheel on a suitable toolholder assembly so that the wheel will not tend to fracture or crack in use. The most typical common prior art assembly utilizes a first tool ring having a clamping flange adjacently machined to a pilot diameter which fits into the bore of the wheel, and a second ring is provided likewise having a clamping flange and a short pilot diameter adjacent to the clamping flange. The two rings, typically called the "wheel collet" and "wheel flange", respectively, are clamped together against the side faces of the grinding wheel to provide a frictional grip on the wheel sides and thus transmit torque, while supporting the bore of the wheel on the respective pilot diameters. The entire grinding wheel assembly is then carried in a suitable manner on a rotatable tool spindle during the grinding process. Usually, the mass of a thick wheel is substantial enough, thus providing sufficient strength, so that the wheel will not tend to crack or be damaged in use. However, a very thin grinding wheel, in the order of 1/8 inch or so, is more susceptible to breakage, and it is desirable to provide as much bore support as is possible during the grinding process. As the wheel gets progressively thinner in design, the respective pilot diameters become very short on the supporting tool rings, so that eventually they are extremely difficult to machine and hold to precision lengths, since the combined length of the pilot diameters must be shorter than the overall width of the grinding wheel.
To avoid the problems inherent in the prior art and to provide a substantially full and continuous bore support, applicant has devised a unique tool mount wherein the circular tool support sections or pilot diameters of the respective rings are relieved to form cooperating facial teeth and tooth spaces on the two rings, so that as the rings are clamped in assembly with a grinding wheel, the tooth members of one ring enmesh with the tooth spaces of the other ring and vice versa. In such design, the tool rings are adaptable to a variety of thin width wheels, adjustably accomodating the varying width, while maintaining a substantially continuous bore support surface for the rotary tool.